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1.
Water surface elevations (t), vertical surface velocities
and vertical surface acceleration
of wind-generated waves have been measured in a laboratory wind wave channel by using resistance-type wave gauges combined with an electronic differentiation circuits. Probability distributions of the values of (t),
, and
have been determined from the wave records.In an initial stage of wave generation, i.e., when wind waves are generated at short fetches and low wind speeds, the observed distributions for (t),
and
are appreciately good fit to the distributions given by successive sum of a Gram-Charlier series, which has been derived following the formulation of Longuet-Higgins (1963), by taking the weakly nonlinear effect into account.However, when wind waves develop with increasing wind speeds and fetches, the observed distributions deviate gradually from the Gram-Charlier series. Particularly, the deviations are remarkable for the distribution of
.When the wind speed increases, the observed distributions of (t),
and
show the following characteristics: (i) the skewnesses of the distributions of (t) and
decrease slightly, (ii) the skewness of
changes, at some wind speed, from positive small values to relatively large negative values, (iii) the kurtosis of the distribution of (t) decreases slightly but that of
increases slightly and these characteristics seem to depend not so much on fetches, (iv) the kurtosis of the distribution of
increases rapidly. 相似文献
2.
The temporal variation of the partial pressure of carbon dioxide
in surface seawater of Iyo Nada in the western Seto Inland Sea was measured by infrared absorption of carbon dioxide (CO 2) in air equilibrated with seawater. The variation of
from January to late May in 1994 was relatively small (from 270 to 340 atm). on the contrary, the
measured in September 1993 ranged from 200 to 450 atm. It seems that the relative high
observed in the north and the south of Iyo Nada in September were caused by destruction of a stratification owing to tidal currents at straits between Hiroshima Bay and Iyo Nada and Hayasui Straits, respectively. The low
observed in the central Iyo Nada in September was ascribed to a tidal front where high concentrations of chlorophyll-a and a relation between
and chlorophyll-a in negative sense were found. Except the observation in the north of Iyo Nada in September, the
in the surface seawater of Iyo Nada were lowe than the atmospheric
(about 367 atm). The results obtained by this work and Kimoto et al. (1993) lead to the conclusion that Iyo Nada acts as a sink of the atmospheric CO 2 on the average. 相似文献
3.
In-water algorithms for OCTS standard products were developed using in situ data and installed for operationally processing
at NASDA/EOC. This paper describes the in-water algorithms Version 1.0 for chlorophyll a concentration, pigment concentration, and attenuation coefficient at a wavelength of 490 nm. The selected OCTS standard algorithms
(Ver. 1.0) are as follows:
相似文献
4.
The relationship between the scale of the spectral minimum of the first differences in temperature fluctuations L and the local value of the Väisälä-Brunt frequency N has been analysed using the results of more than 600 soundings made in various regions of the world's oceans. Allowing for the series of theoretical and experimental indications of the fact that the vertical scale L at the boundary between the fine structure and microstructure in the ocean exists under the effect of processes of breaking of internal waves and hydrodynamic instability with the formation of turbulent patches, and using the energy relationships, the relationship for a solitary patch has been derived through the determining parameters. Based on two expressions for L, derived experimentally and using the energy estimations, the relationships for the averaged rate of absorption of the wave field energy by patches
and the coefficient of the density vertical diffusion
are derived, which do not contradict a series of independent estimations from in situ measurements.Translated by Mikhail M. Trufanov. 相似文献
5.
Effects of the Ekman friction on the prograde (eastward) flows past a cylinder on a -plane are investigated when
(= R
2/ U, where R is the cylinder radius and U the freestream speed)O(1) and (=2 E
k
1/2/ R
0· O(1) where
is the non-dimensional beta parameter and the ratio of the square root of the Ekman number E
k
multiplied by 2 to the Rossby number Ro multiplied by the aspect ratio (= H/R, where H is the fluid depth). Previous studies without the Ekman friction have shown that the -effect inhibits flow separation for pragrade flows through the asymptotic boundary condition by shifting the region of the adverse pressure gradient toward the rear stagnation point. It is found that the Ekman friction alleviates this -effect on the exterior flow. In the E k
1/4-boundary layer, on the other hand, Ekman friction suppresses the vorticity advection along the wall, which tends to make the boundary layer thickness thin and delay the flow separation. The Ekman friction thus affects flow separation in a complicated manner. Details of the boundary layer structures and the separation angles are described for 0.3<
<4.0 and 0.1< <1.5. 相似文献
6.
A series of measurements of winds and wind-waves were carried out in wind-wave flumes. A data analysis based on the hypothesis
of local equilibrium yielded a new empirical formula on the controversial quantity of roughness height z
0 over the water surface:
, where the nondimensional roughness height
is defined by gz
0/ u
*
2 and the wave-wind parameter ũ by ω
p
u
*/ g, g being the gravitational acceleration, u
* the friction velocity of air, ω
p
the peak frequency of wind-wave spectra. The obtained formula is compared with Charnock's (1955) and Toba's (1979) proposals;
is constant in the former and inversely proportional to ũ in the latter. As in Toba's, this formula immediately leads to a practically important conclusion that the drag coefficient C
d
depends not merely on the usual variable U
10 (wind velocity at 10m height over the water surface), but also on the surface state represented by wind-waves. An explicit
expression is provided for the drag coefficient incorporating the wave-wind parameter; it covers the range of C
d
calculated from most of the previous drag formulas, by varying the wave-wind parameter. 相似文献
7.
In each of six areas with various horizontal scale from 0.4 to 15.6 nautical miles, many surveys with vertical net hauls are made for sampling fish eggs and larvae. Though values of C
A are widely spread in each area, the variance s
2 and the mean m of catch numbers calculated from each survey follow approximately the relation from a Poisson mixture model (PMM). |
相似文献
8.
In the marine environment, colloidal sulfurs often occur due to the redox reaction of sulfide ions and oxygen molecules. It is important to know the spectral refractive index of colloidal sulfurs for the discussion of the light scattering in the region where colloidal sulfurs are formed. We presented new methods to estimate the refractive index from the wave length of maximum absorbance (turbidity) of a nearly mono-dispersed colloidal solution. In these methods, the ripples in a first main maximum of the scattering efficiency, Q
sca
, were taken into consideration. By virtue of these methods, we obtained the spectral refractive index of colloidal sulfurs, m
s
(), at 20°C. The Cauchy's expression of it was given by |
相似文献
9.
The Tushima Current in the east channel was measured in a site of the strong current between Tushima and Iki Islands for 43 days of the winter in 1986. The primary results are:First, it was highly barotropic and flowed northeastward with a mean speed of about 20 cm sec –1. Second, it was decelerated by northeast winds rather than by northwest winds in a frequency range of 0.3 and 0.4 cpd. Third, the scale analysis showed that the Tushima Current is approximately in geostrophic balance. The best empirical relationship between the measured Tushima Current and cross-channel adjusted sea level difference is given by |
相似文献
10.
The amount of penetration of a western boundary current into a marginal sea which is connected to an open ocean by two narrow straits is estimated from a linear, steady and barotropic theoretical model. In this model the western boundary current in the open ocean is driven by a wind stress imposed at the sea surface. The inflow of the water of the open ocean into the marginal sea is caused by the pressure difference between two straits produced by the wind-driven circulation in the open ocean.Main external parameters are combined into two non-dimensional parameters;
and (the ratio of the depth of the marginal sea to that of the open ocean), where b is the distance between north and south boundaries of the ocean, D
0 is the depth of the open ocean, is the latitudinal variation of the Coriolis parameter and R is the coefficient of friction. The friction is assumed to be proportional to the flow velocity.In the limit of infinite the volume transport into the marginal sea is not affected by the width of two straits and . It is mainly controlled by the wind stress and the positions of two straits. For finite values of , however, the volume transport depends considerably on and the width of the straits.Guided by both this model and physical considerations, we obtained a relation between the volume transport into the marginal sea and the external parameters. This relation predicts that about 2 % of the volume transport of the Kuroshio penetrates into the Japan Sea. 相似文献
11.
Recent advances in ocean-circulation research on the Yellow Sea and East China Sea shelves are summarized. Observations using
acoustic Doppler current profilers (ADCPs) suggest that the connectivity of mean-volume-transports is incomplete between the
Tsushima (2.6 Sverdrups; 1 Sv = 10 6 m 3/s) and Taiwan Straits (1.2 Sv). The remaining 1.4-Sv transport must be supplied by onshore Kuroshio intrusion across the
East China Sea shelf break. The Yellow Sea Warm Current is not a persistent ocean current, but an episodic event forced by
northerly winter monsoon winds. Nevertheless, the Cheju Warm Current is detected clearly regardless of season. In addition,
the throughflow in the Taiwan Strait may be episodic in winter when northeasterly winds prevail. The throughflow strengthens
(vanishes) under moderate (severe) northeasterly wind conditions. Using all published ADCP-derived estimates, the throughflow
transport ( V) in the Taiwan Strait is approximated as where V
0, V
1, K are 1.2 Sv, 1.3 Sv, and 157 days, respectively, t is yearday, and T is 365.2422 days (i.e., 1 year). The difference between the throughflow transports in the Tsushima and Taiwan Straits suggests
that the onshore Kuroshio intrusion across the shelf break increases from autumn to winter. The China Coastal Current has
been observed in winter, but shelf currents are obscure in summer. 相似文献
12.
The Alaskan Stream is the westward boundary current of the North Pacific subarctic gyre. In the central region of the North Pacific, the Alaskan Stream serves as a connection between the Alaskan gyre, Western subarctic gyre and Bering Sea gyre. Its volume transport is very important in estimating the magnitude of the subarctic circulation in the North Pacific. In order to clarify its seasonal and interannual variation, we conducted observations along a north-south section at 180° during June from 1990 to 1997. Moorings were deployed from 1995 to 1997. Hydrographic casts were made at intervals of 37 km to a depth of 3000 m. Moorings were set between CTD stations, with Moor1 (Moor2) at the center (southern edge) of the Alaskan Stream. Geostrophic volume transport (referred to 3000 m) revealed large interannual variability in the Alaskan Stream. Average volume transport over the 8 years was 27.5 × 10 6 m 3s -1 with a standard deviation of 6.5 × 10 6 m 3s -1. Maximum transport was 41.0 × 10 6 m 3s -1 (1997) and minimum was 21.7 × 10 6 m 3s -1 (1995). Stable westward flows were observed at Moor1 1500 m (259°, 11.7 cm s -1) and 3000 m (240°, 3.7 cm s -1, 1996–1997 year average). The ratio of eddy to mean kinetic energy ( KE/
) was very small (<0.6) throughout the year. A relatively weak and unstable westward flow was observed at Moor2 at 3000 m depth. Conversely, the average flow direction at Moor2 5000 m was eastward. 相似文献
13.
ＡｎｏｎｌｉｎｅａｒｍｏｄｅｌｆｏｒｎｏｎｂｒｅａｋｉｎｇｓｈｏａｌｉｎｇｒａｎｄｏｍｗａｖｅｓＬｉｕＸｉｎ＇ａｎ,ＨｕａｎｇＰｅｉｊｉ,ＣｈｅｎＸｕｅｙｉｎｇ,ＨｕＺｅｊｉａｎ（ＲｅｃｅｉｖｅｄＯｃｔｏｂｅｒ１５,１９９６,ａｃｃｅｐｔｅｄＡｕｇｕ... 相似文献
14.
在试验水池中,开展了波浪在岛礁地形上演化问题的研究。首先在实验水池中建立了西太平洋某岛礁地形的模型,然后采用改进的JONSWAP谱,由造波机产生不同周期、波高的随机波浪。试验中观察到了不同类型畸形波生成的过程及不同波面形态的畸形波。对偏度、峰度及水深与畸形波要素 Hm/ Hs（ Hm表示波列中的最大波高, Hs为有效波高）的关系进行了详细的分析,同时,对畸形波波高 Hfr与偏度的关也进行了分析。通过对试验结果分析,发现峰度与畸形波要素i>H m/ Hs呈正相关, Hfr增大时相应的偏度也会呈现增大的趋势。此外,水深的变化剧烈时（如斜坡、海山位置）有助于畸形波的发生。 相似文献
15.
Concentrations of thiol compounds, copper-complexing ligands, and total dissolved copper were followed over the course of 1 year (October 2002 until September 2003) in the Elizabeth River, Virginia to evaluate seasonality. Copper-complexing ligand concentrations were determined by competitive ligand equilibration-adsorptive cathodic stripping voltammetry (CLE/ACSV). Thiol detection was carried out by high performance liquid chromatography (HPLC) and calibration using a suite of nine thiol compounds (cysteine, glutathione, mercaptoacetic acid, 2-mercaptoethanesulfonic acid, 2-mercaptoethanol, 2-mercaptopropionic acid, 3-mercaptopropionic acid, mercaptosuccinic acid, and monothioglycerol). Total dissolved copper concentrations reached a January low of 13.1 nM to a June high of 24.7 nM and were found to vary seasonally with higher concentrations occurring from June to September. With a low of 26 nM during April to a high of 56 nM in October, copper-complexing ligand (average log K′ CuL of 12.0 ± 0.2) concentrations displayed a similar seasonal pattern to that of total dissolved copper. Free cupric ion concentrations remained below 1.5 pM for a majority of the year except during March, April, and December when values reached pM levels greater than 1.5. Six of the nine thiol compounds surveyed were detected in the Elizabeth River samples and ranged in concentration from below detectable concentrations (< 5 nM) to individual highs ranging from 25.3 to168.5 nM. The thiol compound concentrations displayed a clear seasonality fluctuating at below detection limits during November to February then increasing with increasing surface water temperatures from March to July. CLE/ACSV was used to assess whether or not the suite of thiol compounds detected by HPLC could contribute to the copper-complexing ligand pool. Conditional stability constants for each one of six thiol standards (average log K′ CuL 12.1 ± 0.5) were found to be statistically equivalent to the naturally occurring copper-complexing ligands (average log K′ CuL 12.0 ± 0.2). This suggests that these thiol compounds could act as copper-complexing ligands in natural samples and could contribute to the copper-complexing ligand pool detected by CLE/ACSV. This study involving seasonality of copper-complexing ligands and thiols in an industrialized, urban estuary underscored several points that have to be substantiated in future research efforts including copper-complexing ligands sources and the role that thiol compounds as well as other unidentified organic compounds play in the copper-complexing ligand pool. 相似文献
16.
The present paper examines the adequacy of different probability density functions to describe the peaks, troughs and peak-to-trough excursions of wind waves measured in the coastal zone of the Bulgarian part of the Black sea. For that purpose various theories for non-Gaussian random process are applied. Some theories depend on the mean, variance and coefficient of skewness γ3 of the process. Others also take the coefficient of kurtosis γ4 into consideration. The analyzed field data are gathered in the coastal zone of the Bulgarian part of the Black sea with depth decreasing from 18 to 1.3 m. The measurements are carried out simultaneously for 11 points with time series of 20 min duration. The coefficients of skewness and kurtosis in those time series are expressed as functions of depth and spectral peak frequency. Analogous dependencies on depth of other parameters are also found. As a result of the investigation it is concluded that the probabilities of occurrence of large wave crests and heights are underpredicted by all of the theories considered. 相似文献
17.
The relation between the intensity of breaking of individual wind-wave crests and parameters of wave size and wave form ( e. g., height, period, steepness and skewness) is examined, and the process of change of these parameters is studied in a wind-wave
tank (reference wind speed 15 m sec −1, fetch 16 m). Distributions of the wave form parameters are different for breaking and nonbreaking waves. Fully breaking
waves seem to hold the relation H ∞ T
2, where H is the individual wave height and T is the period. The condition of breaking is not simply determined by the simple criterion of Stokes' limit. Wave height and
steepness of a breaking wave are not always larger than those of a nonbreaking wave. This suggests the existence of an overshooting
phenomenon in the breaking wave. The wave form parameters are found to change cyclically in a statistical sense during the
wave propagation. The period of the cycle in the present case is estimated to be longer than four wave periods. An intermittency
of wave breaking is associated with this cyclic process. Roughly speaking, two or three succeeding breaking-waves sporadically
exist among a series of nonbreaking waves along the fetch. 相似文献
18.
A low-blank pre-concentration procedure is described for the analysis of picomolar iron (Fe) in seawater by isotope dilution high-resolution inductively coupled plasma mass-spectrometry (HR-ICPMS). The procedure uses a two-step Mg(OH) 2 co-precipitation procedure to extract Fe from a 50 ml seawater sample into a 100 μl 4% nitric acid (HNO 3) solution followed by HR-ICPMS measurement. The high pre-concentration ratio ( 500:1) achieved by the procedure minimizes the Fe blank due to ICPMS instrumental Fe background and results in a detection limit of 2 pM and a precision of 4% at the 50 pM Fe level. The measurement of a low-Fe seawater sample spiked with gravimetric Fe standard shows that the method can clearly distinguish 0.01 nM Fe from 0.02 nM Fe in seawater with high accuracy. The method is demonstrated by the analysis of dissolved Fe in the equatorial Pacific Ocean. 相似文献
19.
This paper presents the results of observation on the development of wind-waves which were generated in a lake water about 420 cm deep with a fetch 12 km long. Measurements of surface elevation were carried out at the end of an observational pier where the water depth was 80 cm. The wave momentum flux, i.e., the growth rate of the wave momentum, was estimated from both significant waves and power spectral densities for the wave records. The values obtained by the two ways accorded fairly well and they were 57 % as large as the wind stress measured simultaneously. The exponential growth rate of spectral densities for a frequency component was in good accord with that observed by Snyder and Cox (1966) and by others. If these growth rates are applied to all the components of the spectrum, the wave momentum flux must exceed the wind stress. This cannot explain the experimental results nor can be physically accepted. The difference of spectral densities between the two successive runs showed that the increase of spectral densities was. limited in several bands of frequency. The phenomena are discussed in relation with the overshoot-undershoot effects studied by Barnett and Sutherland (1968).Observational results suggest that the spectral growth of a certain component is closely related to the spectral densities of other components. Energy exchange among componented waves has not been considered in the theories for generation and development of wind-waves established by Phillips, Miles and others.New generation mechanism suggested by Longuet-Higgins (1969) was found to be able to describe the observed growth rates of the form (f)={(1/2)(t–t 1/2)} 2: the spectral density (f) was proportional to the square of duration t. However, the mechanism can not explain the overshoot-undershoot effects peculiar to the equilibrium spectrum of windwaves.Three frequencies characterizing the discrete distributions of frequency bands where spectral densities increased were examined and three waves corresponding to these frequencies were found to be satisfying the resonance conditions for the wave-wave interactions among three sinusoidal wave trains as studied by Phillips (1960), Longuet-Higgins (1962) and Benny (1962). The interactions are suggested to predict well both the spectral growth proportional to squares of duration and the ceaseless oscillations of spectral densities in an equilibrium spectrum. 相似文献
20.
An experiment was conducted in a small wind-wave facility at the Ocean Engineering Laboratory, California, to address the following question: when the wind speed changes rapidly, how quickly and in what manner do the short wind waves respond? To answer this question we have produced a very rapid change in wind speed between U low (4.6 m s ?1) and U high (7.1 m s ?1). Water surface elevation and air turbulence were monitored up to a fetch of 5.5 m. The cycle of increasing and decreasing wind speed was repeated 20 times to assure statistical accuracy in the measurement by taking an ensemble mean. In this way, we were able to study in detail the processes by which the young laboratory wind waves adjust to wind speed perturbations. We found that the wind-wave response occurs over two time scales determined by local equilibrium adjustment and fetch adjustment, Δ t 1/ T = O(10) and Δ t 2/ T = O(100), respectively, in the current tank. The steady state is characterized by a constant non-dimensional wave height ( H/gT 2 or equivalently, the wave steepness for linear gravity waves) depending on wind speed. This equilibrium state was found in our non-steady experiments to apply at all fetches, even during the long transition to steady state, but only after a short initial relaxation Δ t 1/ T of O(10) following a sudden change in wind speed. The complete transition to the new steady state takes much longer, Δ t 2/ T of O(100) at the largest fetch, during which time energy propagates over the entire fetch along the rays ( dx/dt = c g) and grows under the influence of wind pumping. At the same time, frequency downshifts. Although the current study is limited in scale variations, we believe that the suggestion that the two adjustment time scales are related to local equilibrium adjustment and fetch adjustment is also applicable to the ocean. 相似文献
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